The subject invention is directed to climate control systems for passenger compartments of motor vehicles and, more particularly, to an integrated ventilation mode and temperature control system for controlling the source, temperature, and supply of air delivered to the passenger compartment of a motor vehicle.
In typical motor vehicle heating and air conditioning systems, temperature control is accomplished by adjusting the position of a blend door located in the passenger compartment air supply system duct work. Often, a rotary knob located at the vehicle dashboard or control panel is drivingly connected to the temperature blend door through a mechanical cable or linkage arrangement. The loads required to operate the temperature blend door have generally required relatively rigid control cables and linkages.
Also in typical motor vehicle climate control systems, the ventilation mode is determined by the setting or position of one or more vent dampers located in the air supply system duct work either upstream, downstream, or both with respect to the temperature blend door. The position of a first, or source, vent damper blends recirculated passenger compartment air with outside air. The position of a second, or supply, vent damper determines the path or routing in which the conditioned air moves toward the various outlets into the passenger compartment such as, for example, upward toward the windshield to perform a "defrost" function, downward toward the vehicle floor to perform a "heater" function or midway toward the vehicle occupant to perform a "vent" function. Similar to the temperature blend door control described above, the setting of the one or more vent dampers are controlled by a rotary knob or slidable lever located at the dashboard or control panel of the motor vehicle. The loads required to operate the ventilation mode control dampers have generally required rigid control cables and linkages.
Various proposals to simplify or improve the drive connection between the operating knobs or slide levers and the blend doors or dampers have been presented. However, problems with respect to high operating rotational or sliding force requirements have persisted. Also, the routing of the sometimes rigid drive connections between the knobs, slide levers, blend doors, and dampers adds to the complexity and expense of systems of this type. In addition, readjustment of control cable linkage after installation has also been a problem.
A further drawback to prior systems has been the difficulty of achieving a linear relationship between knob movement and output air temperature. Generally, this has only been achievable through the use of electronic systems or by a mechanical system of cams and rigid push-pull cables. The electronic systems are costly, and the systems incorporating rigid push-pull cables present difficult routing problems, such as described above, that substantially limit their use.
Yet another disadvantage of prior climate control systems of the type considered is that the temperature control and ventilation mode control aspects are typically not integrated into a single unitary drive system for converting linear or rotary movement of control levers and knobs to blend door or vent damper position. The prior systems require a separate housing structure for each function, and thus use separate sub-assemblies for each of the temperature control and ventilation mode mechanisms. A result is that systems of this type are expensive and difficult to install into vehicles on an assembly line during manufacture or in motor vehicle repair shops afterwards. Also, the separate temperature and mode control housings consume a substantial volume of space and often require special mounting accommodations in the dashboard of the motor vehicle.